Nylon carrier for polymer concentrate, and films and packages made with the concentrate

ABSTRACT

Improved polymer additive concentrate compositions used in nylon film layers. The improved concentrate comprises a carrier of a nylon polymer composition and the additive material. Preferred nylons includes nylon 6; nylon 6,66; nylon 6,6; and combinations thereof. Preferred additives are antiblock agents and slip agents. The film layers may comprise a single layer nylon film, or may be part of a multiple layer composition. The films are susceptible to being used in making packaging.

BACKGROUND OF THE INVENTION

This invention pertains to the use of nylon in packaging, and especiallywhere additives are to be incorporated into the nylon composition.

Typically, polymer compositions are supplied to fabricators as pellets.It is most convenient that any material which is to be incorporated intothe polymer composition in the fabrication of a shaped product with thepolymer also be in the form of pellets. The fabricator can then mix theappropriate quantity of the additive pellets with the polymer pellets toobtain the desired composition of polymer plus additive.

Additives, in general, are not obtained from their manufacturers inpellet form. For example, slip agents are typically oily in nature andare not susceptible to being fabricated directly into pellets. Antiblockagents are solid in nature, and their fabrication into pellets the sizeof the polymer pellets delivered by the polymer manufacturer wouldprevent their proper dispersion in the overall polymer composition whenan article is fabricated from the polymer. It is critical that solidparticles be very small in size as compared to the typical size ofpellets delivered by the polymer manufacturer. Such polymer pellets areof the order of 3 mm diameter by 3-10 mm in length, for example.

In some cases, additives can be injected directly into an extruderduring the extrusion process of fabricating a film. This is one way inwhich liquid slip agents are incorporated into extrusion operations.

Another common method of incorporating additives into a polymercomposition at the time that a polymer is fabricated into a specificarticle is to first form a concentrate with the additive. Forming theconcentrate consists of mixing the additive material into a polymericcarrier in an amount substantially greater than the amount anticipatedto be used in the final product. In general, the greatest economy ofprocess is obtained where the additive material is incorporated into theconcentrate in as great an amount as possible. For example, someadditives can be incorporated into the concentrate in an amount of about20% additive and 80% polymer. Others can be incorporated in amounts ashigh as 40% to 50%. Still others can be incorporated in amounts as highas up to about 80% additive, 20% polymer.

Each combination of additive and carrier polymer will have its ownparticular limitations as far as the maximum amount of additive whichcan be incorporated into that concentrate. The limitations may be, forexample, the amount of the additive which may bleed out of theconcentrate if the additive is generally of liquid nature. Thelimitation may, rather, be related to the abrasiveness of solidparticulate additive materials such as silica, where the limitation ismore one of the ability of the polymer to serve as a lubricant toprevent the abrasiveness of the solid silica material from severelyeroding the equipment used in mixing, or otherwise forming theconcentrate composition.

Certain types of additives such as pigments and fillers are incorporatedinto the final product, such as molded articles, in such large amountsthat the additive comprises at least 20% to 50%, and sometimes up to 80%by weight of the composition of the final product. In such cases, wherethe additive comprises a relatively large fraction of the overallcomposition, it is well accepted that the carrier polymer for additiveconcentrates makes a significant contribution to the physical propertiesof the final product. So, the concentrate carrier polymer is carefullyselected, as a polymer which supports the desired polymer properties.Typically, the selected concentrate carrier polymer is readily mixablewith the base polymer to make a uniform blend. Thus, it is common forthe concentrate polymer to be selected from the same family as the basepolymer. Within this context, for example, a pigment or filler materialto be incorporated into a polypropylene base polymer composition in anamount of 30% by weight is typically compounded into a concentrate usinga polypropylene or a propylene copolymer as a carrier polymer.

On the other hand, where small amounts, namely less than 10%, of anadditive material are to be incorporated into a base polymer,conventional practice has been to generally disregard the physicalproperties of the additive concentrate carrier polymer, and to assumethat especially the physical properties of the final product will becontrolled by the properties of the base polymer. In that light, theselection of an additive concentrate is based heavily on the additivecontent, with little significance being attributed to the carrierpolymer. As such concentrates are typically used in amounts of less than5% by weight, most commonly about 2%-3%, conventional knowledge holdsthat the composition of the carrier polymer can safely be ignored. Thus,the readily available concentrates using olefinic carriers such asethylene and its copolymers are conventionally used, and are routinelyspecified for use, in small amounts in such engineering resins as nylon,polyester, and the like.

Additive concentrates are available commercially, and are used insubstantial quantities in modifying the properties of a wide variety ofpolymer compositions. The inventors herein have found that thesecommercially available concentrates work relatively well with certainpolymers, and especially chemically related olefin polymers andcopolymers; but that the commercially available additives tend to causecertain reductions in desirable properties when incorporated into nyloncomposition, even in small amounts. For example, the haze level isincreased and the tensile strength tends to be decreased, with additionof only 2%-3% conventional additive concentrate. Certain of the otherstrength properties are likewise somewhat degraded by the incorporationof the concentrate additive. However, in some cases, it is highlydesirable to include the additive composition in the nylon to obtaincertain desirable properties. In those applications, the instantinventors have found that the incorporation of even small amounts of theadditives to obtain the benefits thereof includes the undesirable sideeffect of reduction in other desirable properties.

It is an object of this invention to provide nylon compositions andfilms with small amounts of additive concentrates wherein thecompositional combinations attenuate the reduction in the desirableproperties of the nylon while incorporating into the nylon theadvantageous properties of the additives.

It is another object of the invention to provide multiple layer filmsincluding a layer of nylon which incorporates the concentrate, thecombination being responsible for attenuating the reduction in thebeneficial nylon properties.

It is yet another object to provide packages made with films having theimproved nylon compositions.

SUMMARY OF THE INVENTION

Certain of the objects of the invention are obtained in a film which hasno more than 10% by weight of a polymeric additive concentratecomprising 20% to 85% by weight of a nylon polymer composition and 80%to 15% by weight of an additive, especially a solid, particulatematerial capable of functioning as an antiblock agent. Since slip agentsare usually used in small amounts, they are also included as acceptableadditions in the instant invention. Antiblock agents are preferablyselected from the group consisting of inorganic spheres (especiallythose derived from a combination of silica and alumina), silica, talc,and calcium carbonate, or combinations of the several recited agents.The nylon carrier polymer composition is preferably selected from thegroup consisting of nylon 6,66; nylon 6; nylon 6,6; and combinationsthereof. Preferred compositions comprise 35% to 80%, highly preferably40% to 60% of the nylon polymer composition and 65% to 20%, highlypreferably 60% to 40% of the antiblock agent. Most preferably, thecomposition is 50% to 60% nylon 6 and 50% to 40% of inorganic spheres.Concentrates in the same range may be used with slip agents.

In another respect, the invention is a film comprising a blend of 95% to99.5%, preferably about 97%-98%, by weight of a first nylon compositionand 5% to 0.5%, preferably about 2%-3%, by weight of the additiveconcentrate, wherein the additive concentrate includes the additivematerial incorporated into a second nylon polymer composition. A highlypreferred additive is an antiblock agent, such as earlier described.

Preferably, the first and second nylon polymer compositions arecompatible. The first nylon composition is desirably selected from thegroup consisting of nylon 6; nylon 6,6; nylon 6,66; and combinationsthereof. A highly preferred first nylon composition comprises a mixtureof approximately equal amounts of nylon 6 and nylon 6,66. In anespecially preferred combination of the first and second nyloncompositions, the first nylon composition is a mixture of approximatelyequal amounts of nylon 6 and nylon 6,66, and the second nyloncomposition is nylon 6. It is seen that the melting temperature of thesecond nylon composition of nylon 6 is higher than the meltingtemperature of the first nylon composition of a blend of equal amountsof nylon 6 and nylon 6,66.

The nylon compositions having the novel concentrates disclosed hereinare generally susceptible of being fabricated into the same products(but with improved properties) which can be made from nylon compositionsusing other conventionally available additives. In addition, thecompositions may be used in certain difficult forming conditions tofabricate especially films of a quality not otherwise obtainable usingthe same nylon composition, but with conventional small amounts ofconventional concentrate additives. The novel nylon compositions areespecially advantageously used in fabricating single and multiple layerfilms for use in packaging. Particularly, the modified nyloncompositions, using the novel concentrates herein are advantageouslyused in making multiple layer films having first and second surfacelayers. One of the surface layers comprises the nylon compositionsincorporating the novel concentrates in it. The other surface layercomprises a polymeric composition capable of forming a heat seal whenheat is applied to the nylon surface layer and driven through the filmto the other surface.

The films of the invention may be used in the fabrication of packages.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Additive concentrates are conventionally available wherein the additivematerial has been incorporated into a polymeric carrier such as lowdensity polyethylene, ethylene vinyl acetate, ethylene methyl acrylate,ethylene methacrylic acid, and others of the ethylene polymers andcopolymers. Additives are typically incorporated into polymer carriersby melting the polymer carrier, mixing the additive into the meltedpolymer to achieve a uniform dispersion, then extruding pellets andsolidifying the pellets. Achievement of a uniform dispersion in theconcentrate is important to achieving uniform properties in the finalproduct. It is, of course, advantageous to the compounder of additiveconcentrates to operate the concentrate compounding process with thesame materials for as long a period as possible, to minimize theunproductive downtime associated with material changes. The process ofchanging materials, and especially the polymer carrier in the mixingequipment, may include, for example, a shutdown of the equipment, andsometimes a dismantling of the equipment for cleaning of its internalsurfaces. Since shutdown, dismantling of equipment, and hand cleaningare so costly, compounders of additive concentrates generally providetheir concentrates within families of polymers that are narrowly definedin terms of their polymeric composition ranges. For example, compoundersnormally make concentrates whose carrier polymers are confined to theolefin family of polymers; and especially ethylene polymers andcopolymers.

Similarly, equipment which is designed to melt and mix ethylene polymersand copolymers is generally less adapted for forming uniformly blendedmixtures of additives in other families of polymeric compositions.Properties such as melting temperature, softening temperature,viscosities, sheer rates, and the like vary so much with individualpolymers that the compounding of uniform mixtures of polymers depends onthe equipment available; as different equipments are required fo theefficient processing of different polymers.

Additive concentrates conventionally available have been generallylimited to the propylenes and ethylenes, and especially low densitypolyethylene, and certain of the ethylene copolymers such as ethylenevinyl acetate, and ethylene methyacrylic acid.

Polymer additive concentrates commercially available from concentratecompounders typically contain a minimum of 20%, typically 40% to 60%,and up to 80% of the additive component, with the balance of theconcentrate composition comprising the carrier polymer. The concentrateis typically incorporated into the polymer composition of the finishedproduct in an amount no greater than 10% by weight of the final polymercomposition overall. Normal ranges of concentrate addition into apolymer composition are 0.5% to 5% by weight, most commonly 2% to 3%.The lower threshold of 0.5% represents the minimum amount of an additiveconcentrate which normally is needed to effect a noticeable change in aproperty of the polymer compound. Where smaller amounts are effective,they will apply.

It has been commonly accepted that the concentrate is present in thepolymer composition of the finished product in such a small amount thatthe properties of the polymer which comprises the carrier in theconcentrate can usually be safely ignored when determining or predictingthe properties of the overall finished product polymeric composition.Surprisingly, the applicants herein have found that when the additiveconcentrate is to be used to modify the properties of a nylon polymercomposition, even in small amounts, substantial benefit can be obtainedby incorporating the additive into a concentrate which uses a nylonpolymer as the carrier in the compounding of the concentrate; even wherethe amount of concentrate used in the nylon polymer composition is lessthan 5%, especially in the range of 2% to 3% by weight, and even as lowas 0.5% of the overall nylon composition.

The concentrate composition is 20% to 85% by weight, preferably 35% to80%, highly preferably 40% to 60%, and most preferably 50% to 60% of thenylon polymer, and conversely 80% to 15%, preferably 65% to 20%, highlypreferably 60% to 40%, and most preferably 50% to 40% of the additivematerial.

While the nylon composition in the concentrate may be selected with asubstantial degree of freedom, and depending on which nylon polymer isanticipated to be used as the basic composition into which theconcentrate is to be incorporated, the nylon carrier in the concentrateshould generally be compatible with the nylon used as the basic materialinto which the concentrate is incorporated.

"Compatible" polymers generally means that the polymers can form ahomogeneous mixture as evidenced in films formed from the mixture by anabsence of whitening on thermoforming, and a low haze, generally below7% haze, at a film thickness of about 3.0-3.5 mils. Tus, a concentrateto be incorporated into a film generally comprised of nylon 6 will befabricated using a carrier polymer which is compatible with nylon 6.Generally, the properties of the carrier polymer will be similar to theproperties of the material into which the concentrate is to beincorporated.

Substantial quantities of packaging films are made with nylon polymerlayers, and especially nylon 6, and nylon 6,66, and mixtures thereof.Nylon 6,66 is generally desirable because it can be processed andfabricated at a relatively low temperature. Nylon 6 is sometimespreferred because it is comparatively inexpensive and has a higher heattolerance. Where even higher heat tolerance applications are dictated,nylon 6,6 may be preferred to meet the heat tolerance requirements.Mixtures of nylon 6 with either nylon 6,66 or nylon 6,6 are generallyknown to yield a polymer composition having intermediate propertiesbetween those of the materials of which they are composed.

An especially preferred nylon composition for use in fabrication ofmultiple layer films for packaging of various food products is a blendof approximately equal amounts of nylon 6 and nylon 6,66. Such blendsprovide a combination of a generally desirable lower heat processingtemperature derived from nylon 6,66, along with some of the higher heattolerance properties derived from nylon 6. A desirable concentrate forincorporation into the blend of nylon 6 and nylon 6,66 uses a carier ofnylon 6.

Especially desirable concentrates for use in this invention areantiblock concentrates which are uniformly mixed throughout a nylonlayer of a multiple layer film. Antiblock agents for use in thisinvention may be any of those generally known for use in nyloncompounds, such as silica, talc, calcium carbonate, and Zeeospheres, orcombinations of these agents. Zeeospheres are inorganic ceramic spherescomprising silica and alumina, and are manufactured by Zeelan Industriesof St. Paul, Minn. Other conventionally known antiblock agents maylikewise be used in the concentrates and polymer blends and films of theinvention.

With respect to antiblock agents, and concentrates incorporating theantiblock agents, a highly preferred concentrate for use in makingpackaging films contemplated for use in packaging food productscomprises 50% to 60% of a nylon 6 carrier and 50% to 40% of theZeeospheres.

The overall composition of the material which is used to form the nylonlayer of the packaging film is at least 90%, preferably 95%, and mostpreferably 97-98% of the first, and primary, nylon polymer composition.Generally, the primary nylon polymer does not exceed 99.5% of thecomposition, as the incorporation of at least 0.5% of the additiveconcentrate is generally necessary in order to obtain significantmodification of the properties of the polymer composition by theconcentrate. Typically 2-3% of the concentrate in the overallcomposition is sufficient to obtain the desired modification ofproperties. In some cases, higher addition rates of the concentrate arenecessary, up to 5%, and in some cases up to even 10% by weight of theoverall composition. Generally, no more than 10% of the concentrate isrequired. Use of over 10% of the additive concentrate generally leads toconsideration of other properties and factors, and thus such practicesare not generally considered part of this invention.

With respect to multiple layer films made using the novel nyloncompositions disclosed herein, and especially those incorporating theadditive concentrates using a nylon carrier, a preferred film structurehas a first surface layer comprising the novel nylon composition and asecond surface layer comprising a polymeric composition which is capableof forming a heat seal when heat is applied to the nylon surface layerand driven through the film to the second surface layer. The secondsurface layer is generally considered to be a heat sealing layer.Exemplary of materials which are typically used in the heat sealinglayer in such structures are ethylene vinyl acetate, ionomer, lowdensity polyethylene, and the like.

Exemplary of multiple layer film structures using the novel concentratesand additive-modified nylon compositions of the invention are asfollows.

    ______________________________________                                        (a) /N/tie/E/tie/seal/          3-6 mils                                      (b) /N/E/tie/EVA/seal/          3-6 mils                                      (c) /N/tie/E/tie/seal/LDPE/N/tie/E/tie/seal/                                                                  7-11 mils                                     (d) /N/tie/E/tie/seal/LDPE/N/E/tie/EVA/seal/                                                                  7-11 mils                                     (e) /N/E/tie/EVA/seal/LDPE/N/E/tie/EVA/seal/                                                                  7-11 mils                                     ______________________________________                                         N = Nylon                                                                     tie = Polymeric adhesive material. Exemplary of known adhesives are the       Plexars, CXA's, and the like.                                                 E = Ethylene vinyl alcohol copolymer.                                         seal = Heat sealable polymer compositions, such as ionomer, EVA, LDPE, an     LLDPE.                                                                        EVA = Ethylene vinyl acetate.                                                 Additionally, the invention may be embodied in nonbarrier type films, suc     as (f)                                                                        (f) /N/tie/seal/                                                         

The films of the invention, and as illustrated in the above structures(a) through (f) are readily adapted for use in fabricating packageswhich are especially useful for packaging food products. The films areespecially adapted for use in fabricating pouches, such as preformedbags, as are conventionally used for packaging food products, such asform, fill, and seal bags, and such as for providing lids onthermoformed trays. The films may, or may not be thermoformed. Any ofthe films are readily adapted for being thermoformed into trays.

Especially with respect to the (a) structure, a highly desirablecomposition for the nylon layer is 48.5% nylon 6, 48.5% nylon 6,66, and3% of a concentrate comprising 60% nylon 6 and 40% Zeeospheres. The tielayers are carboxy modified ethylene vinyl acetate compositions. Thesealant layer composition is, for example, an ionomer, an EVA, a LDPE,or a linear low density polyethylene (LLDPE). Other heat sealablepolymer compositions will be obvious to those skilled in the art.Preferred thickness of the film is about 3 mils to about 5.5 mils whenthe film is to be used either in fabrication of a pouch or as lidmaterial over a thermoformed tray. The structures (a), (b) and/or (f)may be combined by the use of any of the known means of combining films,such as adhesive lamination or extrusion lamination, in fabrication ofthicker structures, such as (c)-(e). The thicker structures are thentypically used in fabrication of thermoformed trays, with the thinner(a) and (b) structures being used as lid material over the thermoformedtrays. Conventionally known sheet materials may be used as lidstock withthe thicker forming films of this invention, such as structures (c)-(e).

The comparative improvements recited herein address the properties ofcompositions and films of the invention which, as described,functionally include only the base nylon polymer and the nylon-basedconcentrate. Namely, the films of the invention, so compared, arefunctionally free from other components, and especially thepolypropylenes, the polyethylenes, the ethylene copolymers, and the likewhich are conventionally used as carrier polymers in making polymerconcentrates. These properties, of polymers and films of the invention,are compared to properties attained in similar films made with similarlevels of additive Zeospheres, but in conventionally availableconcentrates using, for example, a low density polyethylene carrier.

In typical packaging operations in which the films of the invention areused, the multiple layer sheet is fabricated as by coextrusion. An arrayof receptacles is then formed in the sheet as by simultaneouslythermoforming the sheet into an array of thermoforming molds positionedunder the sheet. The receptacles are then filled with product, and lidmaterial is sealed over the filled receptacles, with accompanying vacuumbeing drawn on the contents during the sealing process. The array offilled and sealed packages is then cut into individual packages, and theindividual packages are discharged from their respective mold cavities.

The process just described is generally operated without the constantattentio of an operator. Thus the packaging material used in theprocess, and especially for fabrication of the thermoformed recetacles,must be especially compatible with use of the respective equipment. Ifan operator were normally present to watch the operation of theequipment, a failure of the packaging material could be corrected andcleared by the operator. However, since an operator is generally notpresent to oversee the operation of the equipment, any failure of thepackaging material may go undetected and may contribute to furtherbarriers and jamming of the machine before the failure is detected. Thusit is critical that the packaging material be especially compatible withthe operation of the equipment and the overall process.

It is especially important that the packaging material not fail duringthe fabrication of the receptacle in the thermoforming step of theoperation. Structures similar to the (a) structure, and usingconcentrates having an LDPE carrier do occasionally fail by forming ahole in the film during the fabrication of the receptacles in thethermoforming operation. The films of the invention have providedsignificant reduction in the number of failures for a given set ofequipment operating conditions, especially noted with respect to theeconomical films in the thickness range of 3 to 4 mils.

Another failure typical of conventional films using the LDPE carrierconcentrate is that the filled and sealed packages, which have been cutapart and are ready for ejection from the molds, tend to occasionallystick in the mold cavity. As a result, when the molds are automaticallyrecycled in the machine for fabrication of another package, a mold whichstill contains a filled and sealed package which has failed to respondto the automatic equipment for ejection of the package from the moldcavity causes subsequent jamming of the machine at the time when themachine attempts to fabricate another receptacle in that mold which isstill filled with the filled and sealed package. The 3 to 11 mil,especially the 7-11 mil, films of this invention, made experimentallyaccording to structures (a)-(e), have had a "0" defect rate with respectto being discharged from the receptacle mold cavity. It is anticipatedthat, in a commercial operation, some low level of discharge failureswill occur. But the failure rate should continue to be well below thatfor packages having conventionally-modified nylon layers using, forexample, LDPE concentrate carrier polymers.

The selection of specifications for a film to be used in a particularpackage forming process depends substantially on the process equipmentand the process operation. Where the packages are formed at the rate of,for example, 20 to 60 packages per minute, thin films, on the order of 3mils to 6 mils thick are typically used. Where the package forming cycleis somewhat slower, for example 8 to 15 cycles per minute, then thickerfilms are typically used, generally on the order of 7 mils to 11 milsthick. The film specification further depends on the temperature towhich the film is heated during the thermoforming operation and the rateof heating the film.

The multiple layer films of the invention are seen to be less sensitiveto the rate of heating by the heat seal equipment, then prior art filmsincorporating the additive concentrate in a lower melting carrier, asthe lower melting carrier, such as an ethylene polymer or copolymer,softens at a lower temperature than the nylon concentrate carriers ofthe films of the instant invention. Thus the films of the invention canbe heated at a faster rate, without sticking to sealing equipment, thancan films using conventional concentrates.

The thermoforming operation may use a vacuum of between 6 and 26 inchesof Hg. Normal operating range for thermoforming processes is about 10 toabout 20 inches of Hg, with the typical operation using 10 to 12 inches.

Table 1 following shows the properties of typical films of theinvention, and the properties of film structures which are similar, butusing conventioal additive concentrates.

                                      TABLE 1                                     __________________________________________________________________________                     Amt of                                                                        Conc.          Con-         Haze                                              in  Thick-     centrate     Before                                                                             After                       Embodi-                                                                            Example                                                                              Structure                                                                          Nylon                                                                             ness,      Carrier                                                                            Friction.sup.5                                                                        Thermo-                                                                            Thermo-                     ment No     Type Layer                                                                             mils                                                                              Additive                                                                             Polymer                                                                            K.sub.I                                                                           K.sub.F                                                                           form form Gloss.sup.1                                                                       Tensile            __________________________________________________________________________    A    1.     (a)  2%  3.5 Zeeospheres                                                                          N.sub.6.sup.3                                                                      .33 .36 5.7  6.9  79  46,421                  2.     (a)  2%  3.6 Zeeospheres                                                                          N.sub.6                                                                            .35 .33 4.4  4.3  82  44,417                  3.     (b)  3%  3.  SiO.sub.2                                                                            N.sub.6,66.sup.4                                                                   0.7-2+                                                                            1-2+                                                                              3.0  4.2  76  24,855             B    4.     (b)  3%  3.  SiO.sub.2                                                                            N.sub.6                                                                            .5  .6  3.6  5.4  75  23,657                  5.     (b)  5%  3.  Talc   N.sub.6                                                                            .4  .5  5.6  9.8  73  21,778                  Comparative                                                                          (b)  3%  3.  SiO.sub.2                                                                            LDPE .3  .3  6.2  16.6 72  20,963                  #1                                                                            6.     (b)  2%  3.  Zeeospheres                                                                          N.sub.6                                                                            --  --  4.7  6.6  71  17,413             C    Comparative                                                                          (c)  2%  3.  Zeeospheres                                                                          LDPE --  --  6.5  18.9 68  17,146                  #2                                                                       __________________________________________________________________________     .sup.1 45° Angle                                                       .sup.2 Normalized per Nylon as fraction of the film.                          ##STR1##                                                                      .sup.3 N.sub.6 = Nylon 6                                                      .sup.4 N.sub.6,66 = Nylon 6,66                                                .sup.5 K.sub.I = Coefficient to initiate sliding. K.sub.F = force to          continue existing sliding.                                               

Films of Examples 1-6 represent three related embodiments (A, B, and C)of the invention, with the separate embodiments having structurevariations which preclude direct comparison of all the data between theembodiments. Whereas certain of the parameters appear to be consistentthroughout the examples, others are only consistent within their ownembodiments. Examples 1 and 2 represent the A embodiment. Examples 3, 4,5 and Comparative Example 1 represent the B embodiment. Example 6 andComparative Example 2 represent the C embodiment.

Referring to the tensile strength results, in embodiments B and Crepsectively, the tensile strengths of the films of the invention ineach of those embodiments are higher than the tensile strengths of therespective Comparative Examples 1 and 2 of the prior art. Thus, the useof the nylon carrier polymer in the concentrate appears to result in animprovement in tensile strength.

With respect to Example 6 and Comparative Example 1, the first layer ofnylon was 0.6 mil thick. The EVOH layer was 0.15 mil. The tie layer wasabout 0.3 mil. The EVA layer was 0.9 mil. The composition of the sealantlayer was ionomer and it was 1.05 mils thick. The concentrate contained60% of the carrier polymer and 40% of the Zeeospheres.

It is seen from Table 1 that the desirable properties of the film areenhanced in the films of the invention, by the novel use of nyloncarrier in the concentrate composition. Improvements are especially seenin the haze level and the gloss. Improvements are also indicated in thetensile strength.

Table 2 shows the results of thermoforming tests in vacuum formingcavities.

                                      TABLE 2                                     __________________________________________________________________________                Concentrate   Film  Nylon as                                      Example     Carrier                                                                              Conc. Amt.                                                                           Thickness                                                                           Fraction of                                                                           Draw                                                                              Observed                          No.    Additive                                                                           Polymer                                                                              in Polymer                                                                           Mils  Film Thickness                                                                        Depth                                                                             Film properties                   __________________________________________________________________________    Comparative                                                                          SiO.sub.2                                                                          EMAA   3%     6     30%     41/4 inch                                                                         Blowout, hazy                     # 3                                                                           7      SiO.sub.2                                                                          N.sub.6                                                                              3%     6     30%     41/4 inch                                                                         Good                                                                          formability,                                                                  clear                             8      SiO.sub.2                                                                          N.sub.6                                                                              3%     6     30%     41/4 inch                                                                         Excellent                                                                     formability,                                                                  clear                             9      SiO.sub.2                                                                          N.sub.6                                                                              3%     6     15%     33/8 inch                                                                         Excellent                                                                     formability,                                                                  clear                             10     SiO.sub.2                                                                          N.sub.6                                                                              3%     6     15%     33/8 inch                                                                         Excellent                                                                     formability,                                                                  clear                             __________________________________________________________________________

It is seen from Table 2 that extruded films using concentrates havingnylon as the carrier polymer were clear, and were thermoformable, at 30%nylon thickness, under conditions too severe for the Comparative Example3 films. The films could still be formed even when the nylon thicknesswas reduced by half, when the depth of the draw was reduced.

Thus it is seen that the invention provides polymeric additiveconcentrates for use in nylon compositions, which attenuate thereduction in the desirable properties of the nylon while incorporatinginto the nylon the advantageous properties of the additives.

It also provides the modified nylon compositions incorporating thereinimproved concentrates which attenuate the reduction in the beneficialproperties of the nylon.

It further provides single and multiple layer films including a layer ofnylon which incorporates the concentrate, the combination beingresponsible for attenuating the reduction in the beneficial nylonproperties.

It finally provides packages made with films having the improved nyloncompositions.

Having thus described the invention, what is claimed is:
 1. A multiplelayer film having first and second surface layers, said first surfacelayer consisting essentially of the composition resulting from thecombining of (i) 90% to 99.5% by weight of a first nylon polymercomposition and (ii) 10% to 0.5% by weight of an additive concentrate,said additive concentrate consisting essentially of 20% to 85% by weightof a second nylon polymer composition and 80% to 15% by weight ofadditive agent selected from the group of materials capable offunctioning as anti-block agents and slip agents, said second surfacelayer comprising a polymeric composition capable of forming a heat sealwhen heat is applied to said first surface layer and driven through saidfilm to said second surface layer.
 2. A multiple layer film as in claim1 wherein said first and second nylon polymer compositions arecompatible.
 3. A multiple layer film as in claim 1 or 2 wherein saidconcentrate comprises 40% to 60% by weight of said second nylon polymercomposition and 60% to 40% by weight of said additive agent.
 4. Amultiple layer film as in claim 1 or 2 wherein said additive agent isselected from the group consisting of inorganic spheres, silica, talc,calcium carbonate, and combinations thereof.
 5. A multiple layer film asin claim 1 or 2 wherein said first nylon polymer composition is selectedfrom the group consisting of nylon 6; nylon 6,6; nylon 6,66; andcombinations thereof.
 6. A multiple layer film as in claim 1 or 2wherein said second nylon polymer composition is selected from the groupconsisting of nylon 6; nylon 6,6; nylon 6,66; and combinations thereof.7. A multiple layer film as in claim 4 wherein said second nylon polymercomposition is selected from the group consisting of nylon 6; nylon 6,6;nylon 6,66; and combinations thereof.
 8. A multiple layer film as inclaim 5 wherein said second nylon polymer composition is selected fromthe group consisting of nylon 6; nylon 6,6; nylon 6,66; and combinationsthereof.
 9. A multiple layer film as in claim 1 or 2 wherein said firstnylon composition comprises a mixture of approximately equal amounts ofnylon 6 and nylon 6,66 and said second nylon polymer compositioncomprises nylon
 6. 10. A multiple layer film as in claim 9 wherein saidadditive agent is selected from the group consisting of inorganicsphere, silica, talc, calcium carbonate, and combinations thereof.
 11. Apackage made with a film of claim
 1. 12. A package made with a film ofclaim
 2. 13. A package made with a film of claim
 3. 14. A package madewith a film of claim
 4. 15. A package made with a film of claim
 5. 16. Apackage made with a film of claim
 6. 17. A package made with a film ofclaim
 7. 18. A package made with a film of claim
 8. 19. A package madewith a film of claim
 9. 20. A package made with a film of claim 10.